pef vs dng

Godfrey DiGiorgi wrote:
> PEF files are always atomic ... one single file ... but if you use
> Bridge+Camera Raw or Lightroom to add IPTC metadata and perform your
> adjustments, and write the adjustments out (rather than keeping them
> hidden in a centralized database), the applications will create .XMP
> sidecar files for each PEF file.
Hmmm, I must be missing something here. Both PEF and DNG are atomic, in
the sense that they're comprehensive and without need of any sort of
"sidecar" file, in terms of the photographic data and metadata itself.
I think/suspect the .XMP "sidecar" files are more in the nature of the
processing instructions you indicated while in Lightroom than anything
/necessary/ for the realization of the image captured in the PEF or DNG
file. At least, that's been my experience with other programs, though I
haven't used Lightroom.
--
Thanks,
DougF (KG4LMZ)